JPS5871904A - Improved linear medium-to-low density polyethylene composition - Google Patents

Abstract

PURPOSE:To obtain titled polymer composition, while retaining original merits, of improved transparency, melt tension, melt elasticity, etc., by incorporating a radical initiator in linear medium-to-low density polyethylene with specific density and melt index followed by melt kneading. CONSTITUTION:Titled polymer composition with a ratio (MI)2/(MI)1 of 0.05-0.9 can be obtained[where (MI)1 and (MI)2 are the melt indices of the original and improved polyethylene, respectively]by incorporating 0.0005-0.1wt% of a radical initiator in linear medium-to-low density polyethylene having a density of 0.90-0.94g/cm<3> followed by homogeneously melt kneading at a temperature between the melting point and thermal decomposition point of the original polyethylene. For said radical initiator, di-t-butyl peroxide is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to linear medium-low density polyethylene compositions having improved properties.

Linear medium-low density polyethylene produced by copolymerization of ethylene and α-olefin has higher tensile strength, impact resistance, rigidity, and environmental resistance than highly branched low-density polyethylene produced by high-pressure radical polymerization. Stress crack (ES)
CR) and heat resistance. Therefore, films molded using this linear medium-low density polyethylene, and various products molded by injection, hollow, extrusion, rotary molding, etc., are made from highly branched low density polyethylene, even if they are lightweight and thin. It can compete well with other products,
It has high industrial value from the viewpoint of resource conservation and energy consumption. Furthermore, because linear medium-low density polyethylene is superior in various properties as mentioned above, it can be used under more severe conditions than highly branched low-density polyethylene, making it a highly functional product. From this point of view as well, it has high industrial value.

However, such linear medium-low density polyethylene has the following drawbacks compared to highly branched low-density polyethylene. Poor transparency, poor commercial value in terms of appearance,
In addition, due to the low melt tension and low melt elasticity, it is difficult to produce a variety of molded products in blow molding, extrusion molding, film molding, etc., and the processing and molding conditions must be adjusted to narrow conditions. There are industrial disadvantages, and in order to overcome these disadvantages, processing machines must be improved to special specifications, which is economically disadvantageous.

The present inventors have carried out research to improve the excellent properties of linear medium-low density polyethylene and to develop an improved composition, and as a result, they have completed the present invention. That's what happened.

That is, in the present invention, a mixture of linear medium-low density polyethylene and a radical generator in an amount of 0.0005 n or more and less than 0.1 A linear medium-low density polyethylene composition modified by uniformly melt-kneading at a temperature, the composition comprising: (1) a linear medium-low density polyethylene composition having an opening, cio
y/cnt or more and less than 0.94 ylct1, (
11) Melt of the linear medium-low density polyethylene before modification.
The melt index of the linear medium-low density polyethylene composition obtained by modifying the index (MI) by 1% is (MI).
MI) When set to 2, (MI)! /(MI)1 value is 0
．． This relates to a polyethylene composition that has been modified to have a molecular weight of 0.05 or more and 0.9 or less.

According to the present invention, linear medium-low density polyethylene has excellent tensile strength, impact resistance, rigidity, ESCR, and heat resistance, and properties that are disadvantageous to linear medium-low density polyethylene,
For example, a polyethylene composition of high industrial value with improved transparency, low melt tension, low melt elasticity, etc. can be obtained.

When a radical generator is added to polyethylene and melt-kneaded, intermolecular bonding of the polymer occurs, a crosslinking reaction occurs, and its melt viscoelastic behavior, mechanical properties, or thermal properties change. It is well known that crosslinked polyethylene is utilized in various applications such as electric wire coatings and foamed molded products.

In addition, the technology of chemically crosslinking polyethylene has been developed for a long time, and has been developed since ancient times.
82, etc., and various improved techniques have been proposed since then, such as Japanese Patent Publication No. 39-18546, = 5- Japanese Patent Publication No. 4B-1711, Japanese Patent Publication No. 49-18101, Japanese Patent Publication No. 50-23063, etc.

However, these conventional techniques are based on highly crosslinking polyethylene to such an extent that swelling occurs (to a state where gelation occurs) in a solvent such as xylene.

Furthermore, there is no disclosure whatsoever that when the polyethylene before crosslinking is a specific linear medium-low laid polyethylene as in the present invention, the effectiveness is significantly manifested.

In the present invention, specific linear medium-low density polyethylene is used, and the degree of crosslinking is slight, and swelling in solvents such as xylene is unlikely to occur, that is, gelation does not occur. It is characterized by generating a slight degree of crosslinking or intermolecular bonding (in the present invention, to distinguish this mild crosslinking or intermolecular bonding from general strong crosslinking, it is particularly referred to as denaturation). It is something.

On the other hand, when certain polyethylene is used together with a radical generator,
A method of obtaining polyethylene with high die swell by processing it in an extruder at a temperature higher than the melting temperature was introduced in the 1970s.
0-14672. However, in this method, as the polyethylene before modification, there is no technical recognition that especially linear medium-low density polyethylene as shown in the present invention shows remarkable improvement effects in various properties by modification as shown in the present invention. I can't see it. Moreover, compared to the present invention, the amount of radical generator used is much larger, and the obtained effects are also different.

Japanese Patent Publication No. 36-14034 also proposes a method of modifying the properties of polyethylene by reacting a specific polyethylene with a radical generator. However, this method is concerned with ethylene-α-olefin copolymers, especially those with a low α-olefin content, that is, with high density; There is no disclosure of low ethylene-alpha olefin copolymers.

Furthermore, in both Japanese Patent Publications No. 50-14672 and No. 56-14054, the amount of double bonds in polyethylene is an important key, but in the present invention, the amount of double bonds is not so important. . This is because in the present invention,
Because the amount of α-olefin, which is a copolymerization component, is relatively large,
The number of tertiary carbons is large, and the tertiary carbons form radicals using a radical generator to form intermolecular bonds, so it is thought that the double bond does not have much significance.

The present invention will be explained in detail below.

The linear medium-low density polyethylene of the present invention refers to a transition metal oxide catalyst such as an E7 chromium oxide catalyst using silica or alumina as a carrier, or a transition metal oxide catalyst such as a titanium halide or a vanadium halide. metal halide;
From combinations with organoaluminum-magnesium complexes such as algylaluminum-magnesium complexes, argylalkoxyaluminum-magnesium complexes, organoaluminiums such as alkylaluminiums or alkylaluminum chlorides, and other organometallic compounds of groups I to III. Suspension polymerization, solution polymerization, gas phase polymerization, and 1000 to 300 θ atmospheric pressure, 150 to 300°C using catalysts other than dangerous radical generators, such as coordination catalysts.
α-olefins such as ethylene and propylene, phthene-1, pentene-1, hexene-1,4 methylpentene-1, octene-1, and decene-1, which are produced by various processes such as high-pressure polymerization using It is a copolymer with one or more rods, and the density is 0.90977 or more and 0.9
Refers to less than 4 y/c-r/1. The amount of α-olefin in the linear medium-low density polyethylene is 2.6% by weight.
The content is 25% by weight or less. In the present invention, a more preferable density range is 0.91 y/cr/1 or more 0.9
When the density is within this range, the effect of modification by the radical generator of the present invention is maximized, and physical, chemical, mechanical, thermal, optical properties, etc. The effect of improving various properties is greatest.

Examples of the radical generator used in the present invention include benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2
, 5-di(t-butylperoxy) 9-hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne, 1.6-bis(t-butylperoxyisopropyl)benzene , t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, di-t-butyl-shiba-oxyphthalate, t-butyl peroxymaleic acid, inpropyl percarbonate, and other organic peroxides, azobis Examples include azo compounds such as isobutyronitrile, inorganic peroxides such as ammonium persulfate, and these may be used alone or in combination of two or more. Also, among these, the decomposition temperature at a half-life of 1 minute is 170°C.
di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,
5 di(t-butylperoxy)hexane, 2,5-dimethyl-2,5di(t-butylperoxy)hexane, 1
．． 3-bis(t-butylperoxyisopropyl)benzene is particularly preferred.

As a method for modification with a radical generator, the radical generator is added to the -10- linear medium-low density polyethylene, and the resulting mixture is thoroughly mixed with a stirrer such as a ribbon blender or a Henschel mixer, and the resulting mixture is extruded. This is a method of uniformly melting and kneading using a mixer or mixer. The extruder and mixer used for cross-conducting may be either single-screw or double-screw types, but more uniform cross-conductors,
In order to obtain a degree of modification, a double screw type is more preferable. Examples of the double screw type include CIM manufactured by Japan Steel Works, Farrell gFcM, DSM, and Banbury mixer.

The melt-kneading conditions are a temperature higher than the melting point and lower than the thermal decomposition point of the linear medium-low density polyethylene used as the raw material, preferably 14
Examples of conditions include kneading at a temperature in the range of 0°C to 250°C for about 1 to 5 minutes. Further, the atmosphere for melting and cross-talk is preferably an atmosphere with as low an oxygen concentration as possible, for example, an atmosphere sealed with nitrogen, since this produces a uniform polymer structure or does not cause oxidation reactions.

In carrying out the present invention, it is important to control the degree of modification (mild crosslinking reaction). When the linear medium-low density polyethylene is kneaded in the presence of a radical generator at the above-mentioned kneading temperature, intermolecular bonds occur and the melt index (MI) decreases.

In the present invention, when the Ml of the linear medium-low density polyethylene before modification is (MI)l, and the MI after modification (after kneading with a radical generator and modification) is (MI)2. , (MI)2/(MI)l is in the range of 0.05 to 0.9. When the value of (MI)t/(MI)l exceeds 0.9, the degree of improvement in practical characteristics is small. On the other hand, when it is less than 0.05, the degree of modification progresses too much, a gel-like polymer is formed, the polymer structure becomes non-uniform, and molding processability deteriorates, which is practically undesirable.

The degree of modification is adjusted by appropriately selecting the type and concentration of the radical generator, the cross-crossing method, and the conditions, taking into consideration the characteristics of the linear medium-low density polyethylene before modification, additives, etc. The conditions for implementation include that the concentration of the radical generator is 0.0005% by weight or more and 0.1% by weight.
It is necessary to be within the range below. Above (MI)t/
Even if the value of (MI)l is in the range of 0.05 to 0.9, if the amount of radical generator is 0.1% by weight or more, a gel-like substance will be formed and the polymer will become inhomogeneous. or due to decomposition products of radical generators, etc.
This is not preferable since moldability and mechanical properties may become poor. When using twisted and modified linear medium-low density polyethylene for thin films with a thickness of 0.111111 or less, in order to impart excellent melt drawability and reduce fine fish eyes, The value of (MI)2/(Ml)l is more than 0.5 and less than 0.9. To obtain such a degree of modification, the amount of the radical generator is usually less than 0.3% by weight. A particularly preferable range for polymers for blow molding such as extruded sheets and pipes is that (MI)I is 3.
or less, and the value of (Ml)2/(MI)l is 0.05
It is in the range of 0.7. Melt tension, die swell,
Impact strength, ESCR, and other important properties (formability, mechanical properties) are balanced at the highest level.

-13 - The modified linear medium-low density polyethylene composition of the present invention includes, of course, conventional stabilizers, ultraviolet absorbers, antistatic agents, antiblocking agents, pigments, inorganic or organic fillers, rubbers, etc. Other materials normally added to polyolefins, such as small amounts of polymers, can be added. However, although it is possible to add substances that cause an interface reaction with the radical generator, such as ordinary stabilizers and ultraviolet m absorbers, before the modification reaction is completed, it is not possible to add them after the modification reaction is completed. preferable. Examples of these additive substances include B
HT, Ionotsukunu 330 manufactured by Shell, Gutudryte 3114 manufactured by Gutdrich, Irganox 1010.1076 manufactured by Ciba Geigy, Nasvin 32no manufactured by Sankyo Pharmaceutical Co., Ltd., Nor LS 770 manufactured by Sankyo Pharmaceutical Co., Ltd., DMTP.

Examples include DLTDP, calcium stearate, zinc stearate, titanium white, calcium carbonate, talc, styrene-butane diene rubber, ethylene-acetic acid copolymer, and the like.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way. The meanings of the terms used in the examples are as follows: (1) MI: stands for melt index, and is based on ASTM
According to D-1238, temperature 190℃, load 2.16
The measurement was carried out under the condition of kg.

(H) MIR; under MI measurement conditions, load 21.6
It means the quotient of the value measured in kg divided by MI. It is a measure of liquidity. The higher the MIR, the better the fluidity in practical molding processing.

(iii) Density: Measured according to ASTM D-1505.

(IV) Double bond: Measured by infrared absorption analysis using a thin film sample made by compression molding.

The transvinylene, terminal vinyl, and vinylidene bonds were determined from 964.908.888crn'''Irinj, respectively, and expressed as their total.

M comonomer content: The amount of copolymer component contained in the polymer was measured by C''NMR.

(vD Melt tension: Extrude using a rheometer at a temperature of 190'C, plunger speed 2, Ornu/min, stretch this strand at 10 m/min, and let the tension at that time be the melt tension.

(■1) Dice well; outer diameter 16111111. Inner diameter 1
It is expressed as the weight of a 20Cr parison extruded at a temperature of 170°C using a blow molding die manufactured by O.

Sail) Tensile impact strength: Measured according to ASTM D-1822.

(IX) ESCR: Indicates environmental stress fracture resistance. AST
Measured according to MD-1693. Tatami, temperature is 80
℃, and the concentration of nonionic surfactant was 100°C.

It is expressed as the time required for the 50th factor number of test pieces to break.

(x) Plating degree: Measured using a compression molded sheet with a thickness of 0.04H11N according to ASTM D-1003.

(Xi) Film forming properties: Using a film forming machine consisting of an extruder with a diameter of 301, a die gap of 1.51nIAX width 150, a #1III T die, and a roll cooler, the film was extruded at an extrusion temperature of 170°C. The take-up speed was gradually increased, and the film formability and fish eyes in the film were measured. Film formability is judged as "good" when a film can be formed with a thickness of 20μ or less, and 21 to 100.
If the film is cut at a thickness of μ, 1 normal” is 101μ.
The case where the film could only be formed to a thickness above the above was designated as [defective -1].

The fish eye was checked with a spot gauge and was 0.211.
Measure the number of items larger than 11+1φ, and calculate the weight of the film 1
002, 10 or less is "small", 11-10
0 was considered "medium" and 101 or more was considered "high."

Examples and comparative examples of the present invention were carried out on polyethylene and ethylene-α-olefin copolymers using various catalysts and polymerization methods. First, the polymer catalyst and polymerization method used in Examples and Comparative Examples will be explained.

(11 Synthesis of solid catalyst a) Synthesis of solid catalyst used in the following Examples and Comparative Examples
It was carried out using a 10t autoclave.

(1) Solid Catalyst A After removing oxygen and moisture inside the autoclave with dry nitrogen, 4 tons of hexane was introduced and the autoclave was cooled to -17--20°C. A104sMg(”C4I(
0) 2 tons of hexane containing 2.451.2 m0t and 2 tons of hexane containing 1 mot of titanium tetrachloride and 1 mot of monobutyvanadyl chloride were added simultaneously at -20°C under stirring at -20°C. The mixture was added dropwise over 1 hour, and the reaction was continued at this temperature for an additional 2 hours. The reaction mixture was filtered through θj and washed with hexane. This solid catalyst A
It is called.

(11) Solid rigidity medium B (C2H3X n-C4H[l) Si of Mg and hydromethylpolysiloxane with a viscosity of 157 inches
/Mg=1.0/1.0 reactant 3.0mo7 and titanium tetrachloride 3. omot was placed in an autoclave with 6 tons of hexane and reacted at -10°C for 3 hours. The reaction mixture was post-treated in the same manner as in the case of solid catalyst A to obtain a solid catalyst. This is called solid catalyst B.

(iii) Solid catalyst C (sec -CIH9) (n-C,Ho)Mg 2.
Omot Oyohi Vanadyl trichloride 1.5 mot and titanium tetrachloride 1.5 mob (r) a compound, hexane 6
-18- was placed in an autoclave with t and reacted at -20°C for 4 hours. The reaction mixture was treated in the same manner as in the case of solid catalyst A to obtain a solid catalyst. This is called solid catalyst C.

(1) Solid Catalyst D 500 grams of magnesium 11ide and 5 tons of titanium tetrachloride were placed in an autoclave and reacted at 110°C for 3 hours. The reaction mixture was filtered, the solid catalyst was isolated, and washed with hexane. It is called a solid catalyst.

(2) Production of polymer A reactor with a capacity of 200 tons was used to produce a polymer under continuous polymerization conditions. While maintaining the polymerization temperature shown in Table 1, the solid catalyst, organoaluminum compound, α-olefin, and hydrogen were supplied to the reactor under the conditions shown in the table, and the solvent was
0 t/Hr, ethylene polymer production amount 6-10
Polymerization was carried out while supplying the amount necessary to maintain kg/Hr. When the polymerization temperature is 100°C or less, isobutane is used as the solvent and the polymerization pressure is 20 kg/m, and when the polymerization temperature is 120°C or higher, hexane is used as the solvent and the polymerization pressure is 30 kg/cr/m. Polymerization was carried out under the following conditions.

The polyethylene and ethylene-α olefin copolymer used in each Example and Comparative Example were produced using the catalyst and polymerization method described above, and more specifically, under the conditions shown in Table 1 for each example.

Example 1 Production of ethylene-α olefin copolymer as a base for tll i properties Based on the above polymerization equipment and polymerization method, and further using the catalyst and polymerization conditions described in the relevant column of Example 1 in Table 1, A copolymer of ethylene and butene-1 was produced. This copolymer was modified by the method described below, and various characteristic values were measured. The concentration of butene-1 in this copolymer is 7.6% by weight.
, the number of double bonds was 0.38/1000C.

+21 Manufacture of modified polyethylene composition Spray 9F10 liquid of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane as a radical generator onto pellets of the copolymer produced by ill. The mixture was stirred in a Henschel mixer, and then the hexane was evaporated to form a mixture of the copolymer and the radical generator. The concentration of the radical generator was adjusted to 20111'l with respect to the copolymer. This mixture was prepared using a screw with a screw diameter of 60 mIn.
In a φ single screw extruder, seal L1 with nitrogen gas at a temperature of 220 °C and an extrusion speed of about 35 to 9/Hr.
Kneaded and extruded. In this case, the average residence time of the resin in the extruder was 2 minutes and 40 seconds. The thus modified ethylene-butene-1 copolymer was added with 500 ppm of BHT,
Add 500 pills of calcium stearate,
Extrusion was performed again under the same conditions as above to produce a stabilizer-containing modified copolymer composition.

Example 2 A modified copolymer composition was produced in the same manner and under the same conditions as in Example 1, except that the amount of radical generator was changed to 100 p-.

Comparative Example 1 In Example 1, the amount of radical generator was changed to 1500 p-
A modified copolymer composition was produced in the same manner and under the same conditions as in Example 1, except for the following.

= 2 1 - Comparative Example 2 BHT500 was added to the copolymer obtained by polymerizing in Example 1.
Example 1 by adding 500 ppm of calcium stearate and no modification with a radical generator.
An unmodified stabilizer-containing copolymer was produced by kneading and extrusion under the same conditions as above.

Comparative Example 3 Under the polymerization conditions shown in Table 1, high-density ethylene-butene-
1. To prepare the copolymer, add a stabilizer in the same manner as in Example 1,
An unmodified stabilized copolymer was prepared. The butene-1 concentration in this copolymer was 0.8% by weight, and the number of double bonds was 0.47/1. It was 0 0 0 C.

Comparative Example 4 The copolymer polymerized in Comparative Example 3 was modified in the same manner as in Example 1, and a stabilizer was further added to produce a modified copolymer composition. In this case, the amount of the radical generator was adjusted so that the MI after modification was the same as the MI of the modified copolymer in Example 2, and the amount was 9011p1.

- 2 2 = Comparative Example 5 The characteristics of low density polyethylene (Asahi Dow M1B20) manufactured by a normal high pressure method were measured.

Comparative Example 6 The low density polyethylene used in Comparative Example 5 was modified in the same manner as in Example 1. However, the amount of the radical generator was adjusted so that the MI after modification was the same as that of the modified copolymer in Example 2, but the amount was 2901111%.

Comparative Example 7 Under the polymerization conditions shown in Table 1, an ethylene-butene-1 copolymer having almost the same MI and MIR1 density as the modified copolymer in Example 2 was produced, and then in the same manner as in Comparative Example 2, Unmodified stabilized copolymerization [- produced.

Above Examples 1 and 2 and Comparative Examples 1, 2, 3, 4, 5゜6
．． The characteristic values of No. 7 are shown in Table 2.

Example 3 An ethylene-octene-1 copolymer was produced under the polymerization conditions shown in Table 1. Next, this copolymer was mixed with 501'l'l of 2,5-dimethyl-2,5di(t-]'tityl peroxyxin as a radical generator, and the kneading and extrusion temperature was set to 2.
Modification was carried out in the same manner as in Example 1, such as kneading and extrusion conditions, except that the temperature was 00°C. Furthermore, a stabilizer was added in the same manner as in Example 1 to produce a stabilizer-containing modified copolymer.

Example 4 A stable stab-modified copolymer composition was produced in the same manner as in Example 3, except that the amount of the radical generator was changed to 200 μm.

Comparative Example 8 A stabilizer-containing modified copolymer composition was produced in the same manner as in Example 3, except that the amount of radical generator was changed to 1200μ.

Comparative Example 9 A stabilizer-containing unmodified copolymer composition was produced by adding only a stabilizer to the copolymer produced in Example 2 after the modification with a radical generator in the same manner as in Comparative Example 2. . In addition,
The concentration of octene-1 in the copolymer was 8.4% by weight, and the number of double bonds was 0.09/1000C.

Example 5 The stabilizer-containing unmodified copolymer composition produced in Comparative Example 9 was modified in the same manner as in Example 3. However, the amount of the radical generator was adjusted to be the same as the MI of the modified copolymer according to Example 6. The amount was 701,191.

Example 6 The stabilizer-containing unmodified copolymer composition prepared in Comparative Example 9 was modified in the same manner as in Example 3. However, the amount of radical generator was 6509i11.

Comparative Example 10 The stabilizer-containing unmodified copolymer composition produced in Comparative Example 9 was modified in the same manner as in Example 6. However, the amount of the radical generator was LloopIIm.

Comparative Example 11 High-density ethylene-octe/
-1 copolymer was produced, and then a stabilizer was added in the same manner as in Comparative Example 2 to produce a stabilizer-containing unmodified copolymer composition.

The concentration of octene-1 in this copolymer was 2.3% by weight, and the amount of double bonds was 0.11/1o OC.

Comparative Example 12 The copolymer produced in Comparative Example 11 was modified in the same manner as in Example 6. However, the amount of the radical generator was adjusted so that the Ml after modification was almost the same as the MI of the modified copolymer composition according to Example 3. The amount was 55 ppll. A stabilizer was then added as in Example 3.

Comparative Example 13 Under the polymerization conditions shown in the first coating, an ethylene-octene-1 copolymer having almost the same MI and λ''R; density as the modified copolymer composition according to Example 6 was produced. A stabilizer was added in the same manner as in Example 3.

Table 3 shows the characteristic values of Examples 3, 4, 5.6 and Comparative Examples 8, 9, 10°11, 12, and 13.

Example 7 An ethylene-hexene-1 copolymer was produced under the polymerization conditions shown in Table 1. This copolymer was modified with 200 ppm of the radical generator used in Example 1 in the same manner as in Actual Flow Side 1, and then a stabilizer was added.

Comparative Example 14 A stabilizer was added to the copolymer of Example 7 without modification in the same manner as in Comparative Example 2, to produce a stabilizer-containing unmodified copolymer composition. The concentration of hexene-1 in this copolymer is 14% by weight, the amount of double bonds FiO, 33, 71000
It was C.

Comparative Example 15 High density polyethylene was produced under the polymerization conditions shown in Table 1. Next, a stabilizer was added without modification in the same manner as in Comparative Example 2 to produce a stabilizer-containing high-density polyethylene composition.

The amount of double bonds in this polyethylene was 0.48/1000C.

Comparative Example 16 High-density polyethylene according to Comparative Example 15 was modified with 200 ppm of the radical generator used in Example 1 in the same manner as in Example 1, and then a stabilizer was added to form a stable stab-modified polyethylene composition. was manufactured.

Comparative Example 17 Low density polyethylene produced by ordinary high pressure method (Asahi Dow L 1
850 A).

Comparative Example 18 The low density polyethylene used in Comparative Example 17 was modified in the same manner as in Example 1. However, MI after denaturation is Example 7
The amount of the radical generator was adjusted so that the MI of the modified polyethylene composition was almost the same as that of the modified polyethylene composition. The amount required was 450 ppm.

The above Example 7 and Comparative Examples 14, 15, 16, 17゜1
The characteristic values of No. 8 are shown in Table 4.

The following can be said from the characteristic values on each side in Tables 2, 3, and 4.

a Comparison of Examples 1 and 2 and Comparative Example 2, Example 5.4,
From the comparison between 5.6 and Comparative Example 9 and the comparison between Example 7 and Comparative Example 14, the modified copolymer composition according to the present invention has lower melt tension and die strength than the unmodified copolymer. Swell, tensile impact strength, ESCR.

It can be seen that many characteristics, such as the degree of comfort, have been significantly improved.

b From Comparative Examples 1, 8.10, the amount of radical generator is 1
Even if a large amount is used in excess of oooppa, the improvement effect on die swell will be smaller than in the case of less than 100011111, and in addition, the molding processability will deteriorate, such as poor film formability and fish eyes. It only gets worse compared to the combination.

Comparison with clQ Example Stream Side Comparative Example 7, Example 3 and Comparative Example 1
3, a copolymer with the same Ml, MIR, and density (comparative example) made by simple polymerization has lower melt tension, die strength, and die strength than the modified copolymer composition according to the present invention (example). The characteristics of swell and sharpness are = 63- = 32- inferior.

The improved effect of the radical generator of the present invention was observed in the case of linear medium-low density polyethylene (ethylene-α olefin copolymer), and in the case of high-density polyethylene (Comparative Example 3,
4, 11, 12, 15, 16) and highly branched low density polyethylene produced by high pressure method (Comparative Examples 5, 6,
This is particularly impressive compared to '17, 18). In order to make this easier to understand, related data has been extracted from Table 2.3.4 and placed in Table 5.

-34- As explained above, the modified linear low-density polyethylene composition of the present invention has superior melt tension, die swell, transparency, etc. compared to conventional linear medium-low density polyethylene. It is suitable for a wide variety of uses and products.

-36- 43- -35-

Claims (1)

[Claims] 1. Adding 0.0% radical generator to linear medium-low density polyethylene.
A linear medium-low density polyethylene composition modified by uniformly melt-kneading a mixture of 0005% by weight or more and less than 0.1% by weight at a temperature higher than the melting point of the linear medium-low density polyethylene and lower than the thermal decomposition temperature. (1) Linear medium-low density polyethylene ethylene has a density of 0.90
f/c1 or more and less than 0.94 t/Crd, (1
1) The melt index of the linear medium-low density polyethylene before modification is (Ml) 1, and the melt index of the linear medium-low density polyethylene composition obtained by modification is (Ml).
l) When t, (MI)! /(MI)1 value is 0.
1. A modified linear medium-low density polyethylene composition which has been modified to have a polyethylene content in the range of 0.05 or more and 0.9 or less. 2. The value of (Mi), /(Ml) exceeds 0.5 and becomes 0.
．． 9. The composition according to claim 1, which is particularly suitable for use as a film, and is modified to fall within the range of 9 or less. 3. (MI) is less than or equal to 32/10i, and (M
I) The composition according to claim 1, which is modified so that the value of t/(MI)I falls within the range of 0.05 or more and 0.7 or less, and is particularly suitable for extrusion and blow molding. 4. The density of linear medium-low density polyethylene is 0.9'1
7. The composition according to claim 1, wherein p is 7 crtt or more and 0,935 f/C-d or less. 5. The radical generator is di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,
5 di(1-butylperoxy)hexane, 2,5-dimethyl-2,5 di(t-butylperoxy)hexane, 1
．． 5. The composition according to claims 1 to 4, which is 3-bis(1-butylperoxyisoglobil)benzene.